Limit switch assembly manufacturing machine

ABSTRACT

A manufacturing machine such as an automatic assembly machine is disclosed which includes a work station which can include linear motion devices and rotary motion devices. A conveyor system is disclosed for transporting a workpiece to and from the work station, and positioning means are disclosed for precisely positioning the workpiece to the work station.

This is a division of application Ser. No. 752,107 filed Dec. 20, 1976,now U.S. Pat. No. 4,137,432, is a division of application Ser. No.468,260, filed May 10, 1974, now U.S. Pat. No. 3,998,316.

The present invention relates to manufacturing machines, and moreparticularly to machines such as automatic assembly machines in which aworkpiece and suitable tooling are automatically manipulated relative toeach other to assemble parts into the workpiece or otherwise advance themanufacturing process of the workpiece.

A number of forms of machines such as automatic assembly machines havebeen proposed and actually put into use in the prior art. One of theprincipal applications of such machines has been the automaticmanipulation of parts and tools to assemble relatively complexassemblies out of simpler parts or components. In such machines, one ormore work stations are provided, with a parts feeder or the likeprovided at each work station which supplies the parts to be added tothe workpiece at the work station and a conveyor system interconnectingthe work stations to transport the workpiece from work station to workstation, with the workpiece becoming progressively more completelyassembled at each work station.

At the work station, means are provided to position and hold theworkpiece rigidly in place at the work station while suitable tooling atthe work station manipulates the parts or components supplied to thework station by the part feeder to assemble these parts into theworkpiece, thereby advancing the assembly of the workpiece. After thework station had completed its portion of work on the workpiece, theworkpiece is advanced by the conveyor system to the next work station,where another assembly operation is effected on the workpiece.

Obviously, if accurate assembly of the workpiece with low tolerance isto be effected by the work station, the workpiece must be accuratelypositioned while it is being held at the work station during theassembly operation. In the prior art, this has usually been achieved by,in effect, the assembly machine being one large, monolithic structure,with the conveyor and all work stations being rigidly and accuratelycoupled to each other, usually by being secured to a common heavy metalbase plate in which the mounting holes for the conveyor and the workstation have been accurately machined, in order to permit accurate workby the work stations on the workpiece.

Such machines as have existed in the prior art have been of highlyspecialized design to perform the particular automatic assembly functionon a particular type of workpiece. The biggest items and the cost ofsuch machines has been for special engineering, fabrication anddebugging, with only a relatively small portion of the cost being forstandard modules. Some manufacturers have claimed the virtue ofmodularization for their machines, but such modules have usuallyconsisted only of limited portions of the machine, such as conveyors andactuator drive chassis and special purpose mechanisms such as complexbut limited pick and place assemblies.

Because of these above-mentioned limitations in the prior art, suchautomatic assembly machines have been of only limited utility, sincetheir high cost can be justified only in manufacturing operations whichproduce large quantities of parts, such as at least several millionparts per year of the same type. Because of this limitation, most suchmachines have been found in the automobile industry, which is one of thefew manufacturing and assembly operations which require such largenumbers of parts.

It is accordingly an object of the present invention to provide animproved manufacturing machine.

It is yet another object of the present invention to provide an improvedautomatic assembly machine which uses a maximum number of standardmodules, and which requires little special engineering, fabrication anddebugging.

It is a further object of the present invention to provide an improvedautomatic assembly machine of inherently high accuracy and reliabilitybut of relatively low cost.

It is still another object of the present invention to provide a multistation automatic assembly machine in which lower accuracy is requiredin locating the work stations relative to the conveyor than is requiredin relating the work station and its tooling to the workpiece.

It is a further object of the present invention to provide an improvedconveyor system for use in such automatic assembly machines.

It is another object of the present invention to provide an improvedlinear motion module for use in such automatic assembly machines.

It is still another object of the present invention to provide animproved rotary motion module for use in such automatic assemblymachines.

Briefly stated, and in accordance with the presently preferredembodiment of the invention, a manufacturing machine such as anautomatic assembly machine is provided which includes at least one workstation including at least one linear motion device and at least onerotaary motion device. A conveyor system is provided for transporting aworkpiece to and from the work station, and positioning means areprovided for precisely positioning the workpiece relative to the workstation.

In accordance with one of the features of the present invention, thelinear motion device includes a stationary structure including a sparmember, a shaft member and means for supporting the spar member andshaft member in spaced parallel relationship and a moving member whichincludes means for securing thereto the element to be moved. Bearingmeans are provided for attaching the moving member to the spar memberand shaft member for sliding reciprocal movement along a defined pathparallel to the spar member and the shaft member. Controllable drivemeans are provided which are secured to the stationary structure andwhich, when energized, drives the moving member along the defined path.Limit means are provided which are supported by the stationary structureat a predetermined position along the defined path, and control meansare provided which are responsive to the moving member contacting thelimit means to provide a control signal indicating that the movingmember has contacted the limit means.

In accordance with another feature of the present invention, a rotarymotion device is provided which includes a rotary cylinder having ahousing and a rotor and controllable drive means which, when energized,drive the rotor of the rotary cylinder. Support means are provided whichare secured to the housing of the rotary cylinder, and an arm isprovided which is secured to the rotor of the rotary cylinder. Limitmeans are provided which are secured to the housing of the rotarycylinder at a predetermined position around the rotor in a pathtraversed by the arm when the drive means is energized, and controlmeans are provided which are responsive to the arm contacting the limitmeans to provide a control signal indicating that the arm has contactedthe limit means. Means are provided which are secured to the rotor tosupport the element to be moved in a rotary path.

In accordance with another feature of the present invention, a conveyorsystem is provided which includes a conveyor bed whose perimeter definesthe closed loop of the conveyor system, a drive chain which extendsaround the perimeter of the conveyor bed and at least one carriagemember which is driven around the perimeter of the conveyor bed by thedrive chain. The conveyor bed comprises a plurality of alternatelydisposed straight and arcuate sections, with each of the straightsections including a vertical surface and each of the arcuate sectionsincluding a rotatably mounted horizontal wheel. The drive chaincomprises a plurality of roller elements each having a vertical axis ofrotation, with the drive chain extending around the perimeter of theconveyor bed and being in engagement with the wheels of the conveyorbed. The roller elements of the drive chain are in contact with thevertical surfaces of the conveyor bed, whereby, when the drive chain isdriven, the roller elements along the straight sections of the conveyorbed are driven in rotation about their axes by frictional engagementwith the vertical surfaces. The roller elements are carried around thearcuate section of the conveyor bed by the horizontal wheels. By thisarrangement, the outer surfaces of the roller elements have a surfacevelocity equal to twice the velocity of the drive chain along thestraight sections of the conveyor bed and equal to the velocity of thedrive chain along the arcuate sections of the conveyor bed. The carriagemember comprises support means for supporting the carriage member fromthe conveyor bed and means for frictionally driving the carriage memberby the roller elements of the drive chain. The carriage member isthereby driven at a higher velocity along the straight sections of theconveyor bed and at a lower velocity along the arcuate sections of theconveyor bed. The carriage member is further provided with a platen forcarrying a workpiece.

In accordance with yet another feature of the present invention, theprecision positioning means for positioning the workpiece relative tothe work station includes means for removing the platen from thecarriage member, and alignment means supported by the work station forprecisely positioning the platen relative to the work station.

For a complete understanding of the invention, together with anappreciation of its other objects and advantages, please refer to thefollowing detailed description of the attached drawings, in which:

FIG. 1 shows a plan view of a manufacturing machine in accordance withthe present invention;

FIG. 2 shows a plan view of a second embodiment of a manufacturingmachine in accordance with the present invention;

FIG. 3 shows a cross-sectional view taken along the lines 3--3 of FIG.1;

FIG. 4 is a plan view of a carriage member as it is transported aroundthe curved end section of the conveyor bed of FIG. 1;

FIG. 5 is a bottom view of one of the carriage members and a portion ofthe conveyor bed of FIG. 1;

FIG. 6 is an elevational view of a conveyor bed, a carriage member and awork station of FIG. 1, and illustrates relationship of these componentsbefore the platen has been lifted from the carriage member;

FIG. 7 is a top plan view of the arrangement of FIG. 6;

FIG. 8 is an elevational view similar to FIG. 6, but shows therelationship of the components after the platen has been removed fromthe carriage member;

FIG. 9 is a schematic representation of a typical work station inaccordance with the present invention;

FIG. 10 is a plan view of a typical linear motion module in accordancewith one of the features of the present invention;

FIG. 11 is a cross-sectional view taken along the lines 11--11 of FIG.10;

FIG. 12 is a cross-sectional view of a portion of a linear motion moduleof FIGS. 10 and 11, and illustrates details of the control means whichresponds to the moving member reaching the limits of its defined path;

FIG. 13 is a cross-sectional view similar to FIG. 12, and illustratesanother embodiment of the control means which may be used with theinventions;

FIG. 14 is a plan view of a portion of the linear motion module of FIGS.10 and 11, and illustrates a third embodiment of the control means whichmay be used with the present invention;

FIG. 15 is a side view of a typical rotary motion module in accordancewith one of the features of the present invention; and

FIG. 16 is an end view of the rotary motion module of FIG. 15 and alsoillustrates the series connection of two rotary motion modules.

FIG. 1 shows a plan view of a manufacturing machine such as an automaticassembling machine in accordance with the present invention. It is notedthat some portions of the machine of FIG. 1 are merely shownschematically, with the details of these portions of the machine beingshown and described in subsequent figures.

As is shown in FIG. 1, the machine includes a conveyor system 10 whichitself comprises a conveyor bed 12, a plurality of carriage members 14and a drive chain 16 which carries the carriage members 14 around theperimeter of the conveyor bed 12. As is shown in more detail in FIGS. 3through 8 below, the carriage member 14 includes means to carry aworkpiece upon which assembly operations are to be performed. Drivechain 16, which may be a conventional roller chain, transports thecarriage members 14 around the perimeter of the conveyor bed 12 untilthey are adjacent one of the work stations 18, which is merely shownschematically in FIG. 1. Details of a typical such work station areshown in FIG. 9, and described below.

As is shown in FIG. 5, described below, means are provided to disengagethe carriage member 14 from the drive chain 16 when the carriage member14 is adjacent one of the work stations 18, and further means areprovided to remove the workpiece from the carriage member 14 so that thework station 18 may perform the desired assembly and manipulatingoperations on the workpiece. After the assembly and manipulatingoperations are completed by the work station 18, the workpiece isreturned to the carriage member 14, which is then reengaged by the drivechain 16 to be carried to the next adjacent work station 18, whereanother assembly or manipulating operation is performed on the workpiecein a similar manner.

As is shown in FIG. 1, the conveyor bed 12 is itself a modular system,comprising two end modules 20 and any desired number of center modules22, all joined by suitable splice plates 24.

Each of the end modules 20 includes a rotatably mounted horizontal wheelmember 26, which in the preferred embodiment of the invention is asprocket wheel whose teeth engage the links of the drive chain 16 andsupport the drive chain 16. In the preferred embodiment of theinvention, one of the sprocket wheels 26 is also used to impart motionto the drive chain 16. For instance, an electric motor 28 or the like isprovided which drives the sprocket wheel 26 through a belt 30 or thelike.

FIG. 2 illustrates a similar manufacturing machine as is shown in FIG.1, but in which the conveyor bed 12 has a hollow rectangularconfiguraation instead of the narrow linear configuration of FIG. 1. Theconveyor bed 12 of FIG. 2 is formed from eight center modules 22, suchas are shown in FIG. 1, which are interconnected with four cornermodules 32. Again, each of the corner modules 32 incorporates arotatably mounted horizontal sprocket wheel which support the drivechain 16. In the embodiment of FIG. 2, six work stations 18 are shownpositioned around the perimeter of the conveyor bed 12. The arrangementshown in FIG. 2 obviously allows the use of a larger number of workstations 18 and more efficient utilization of floor space in a factoryor the like when a larger number of work stations is required toassemble a particular workpiece.

In either event, in both of the embodiments of FIGS. 1 and 2, it is seenthat the conveyor bed 12 comprises a plurality of alternately disposedstraight and arcuate sections, with each of the arcuate sectionsincluding a rotatably mounted horizontal wheel, such as a sprocketwheel, the perimeter of which defines the curved portion of theperimeter of the conveyor bed.

FIGS. 3 and 4 show details of the carriage member 14 and how it istransported about the perimeter of the conveyor bed 12 by the drivechain 16. FIG. 3 is a cross-sectional view taken along the lines 3--3 ofFIG. 1 and FIG. 4 is a plan view of a carriage member 14 as it istransported around the curve end section of the conveyor bed 12 ofFIG. 1. The following is a description of both FIGS. 3 and 4, with thesame reference numerals being used in each figure to indicate the sameparts and components.

As is shown in FIGS. 3 and 4, there is secured around the perimeter ofthe carriage bed 12 a vertical plate member 40, for example, by a boltand nut 42 or the like. The roller elements 44 of the drive chain 16roll against the outer surface of the vertical plate member 40, and thetop portion 46 of the vertical plate member 40, which may be consideredto be a carriage support rail, actually supports the carriage member 14in a cantilever fashion, as is described below.

The carriage member 14 comprises a carriage body 48 to which arerotatably secured a pair of horizontally disposed roller elements 50 anda single vertically disposed roller element 52 which, as is best shownin FIG. 4, is positioned approximately midway between the horizontallydisposed roller elements 50. As is shown in FIGS. 3 and 4, the rollerelements 50 and 52 engage the top horizontal surface and vertical innersurface of the carriage support rail 46 and support the weight of thecarriage member 14 in a cantilever fashion from the carriage supportrail 40.

The carriage body 48 also includes a vertical drive plate section 54which, when the carriage member 14 is being supported in the cantilevermanner just described, rests against the outer surface of the rollerelements 44 of the drive chain 16. Motion is imparted to the carriagemember 14 by this vertical drive surface 54 engaging the roller elements44 of the drive chain 16, and as is described in more detail below, thisarrangement causes the carriage member 14 to be driven at a speed equalto twice the velocity of the drive chain 16 along the straight sectionsof conveyor bed 12 and at a speed equal to the velocity of the drivechain 16 along the arcuate sections of the conveyor bed 12.

Continuing the description of the carriage member 14, the carriage body48 also includes a horizontally disposed load bearing section 56 whichsupports the workpiece which is to be transported between work stationsby the conveyor system. For example, the workpiece (now shown in FIGS. 3and 4) may be supported on a platen 58 which is itself removablysupported on the portion 56 of carriage body 48 by the alignment pins 60and the posts 62. The structure and function of the platen 58, thealignment pin 60, and the manner in which the platen is removed andreplaced on the carriage member 14 are described in detail in connectionwith FIGS. 6, 7 and 8, described below, so no further description ofthis portion of the system is described in connection with FIGS. 3 and4.

Referring now specifically to FIG. 3, it will be appreciated that, whenthe drive chain 16 is driven, the roller elements 44 rotate about theirown axis because of frictional contact with the vertical plate member40, and that the linear velocity of that portion of the outer surface ofthe roller element 44 which is diametrically opposed to the point ofcontact with the vertical plate member 40 is equal to twice the velocityof the drive chain. This portion of roller element 44 is the point whichis actually in frictional or driving engagement with the vertical driveplate portion 54 of the carriage body 48. If one assumes no slippagebetween these surfaces, then the carriage member 14 is driven by theroller element 44 at a velocity equal to twice the velocity of the drivechain 16. Thus, the carriage members 14 are quickly driven betweenadjacent work stations.

However, referring now specifically to FIG. 4, it will be appreciatedthat when the roller elements 44 of the drive chain 16 enter the arcuatesection of the conveyor bed 12, these roller elements 44 are engaged bythe teeth of the sprocket wheel 26, and are carried around the arcuatesection by these teeth, with no rotation being imparted to the rollerelements 44 about their own axis. Now, since the vertical drive plateportion 54 of the carriage body 48 is still in contact with the outersurface of these roller elements 44, the carriage member 14 is carriedaround the arcuate portion of the conveyor bed 12 at a velocity equal tothe drive velocity of the drive chain 16.

Those skilled in the art will readily appreciate that, since centrifugalforce is a function of the square of the velocity of an object, thecentrifugal forces on the carriage member 14 and on any workpiece beingsupported by carriage member 14 is only one quarter of the centrifugalforce which would be on these elements if the velocity about the arcuateportion of the conveyor bed 12 were the same as it is along the straightportion of the conveyor bed 12. Thus, there is significantly less chancethat the position of the workpiece on the conveyor bed 14 will changebecause of centrifugal force and result in the workpiece being in thewrong position on the carriage member 14 when the carriage member 14reaches the next work station.

FIG. 5, which is a bottom view of one of the carriage members 14 and aportion of the conveyor bed 12, shows the manner in which the carriagemember 14 is disengaged from the drive chain 16 and is positioned with ahigh degree of accuracy relative to one of the work stations when thecarriage member 14 reaches a position adjacent one of the work stations.

As is shown in FIG. 5, a ramp surface 64 is provided which is secured tothe bottom surface of the load support section 56 of the carriage member14. A controllable stop member 66, which may be driven by an aircylinder 68 or the like secured to the carriage bed 12, is provided, andthe air cylinder 68 is energized to move the stop member 66 out into thepath of the ramp surface 64 whenever it is desired to disengage thecarriage member 14 from the drive chain 16. Now, when the drive chain 16moves the carriage member 14 into the stop member 66, the ramp surface64 engages stop member 66, and the carriage member 14 is caused torotate about the carriage support rail 46 of FIG. 3 (not shown in FIG.5). When this occurs, as is shown in FIG. 5, the carriage drive plate 54is moved outwardly away from contact with the surface of the rollerelement 44 of the drive chain 16, and motion is no longer imparted tothe carriage memer 14 by movement of the drive chain 16. Also, it willbe appreciated by those skilled in the art that, when such a rotation ofthe carriage member 14 occurs, the center of gravity of carriage member14 is moved slightly upwardly, and by proper design of the angle of theramp surface 64 and the other dimensions of the carriage member 14, allof the kinetic energy in the moving carriage member 14 is smoothly andgradually transformed to potential energy. The carriage member 14 thusdecelerates smoothly to a stop, with a minimum of shock and resultantposition shift of any workpiece being carried by carriage member 14.

If desired, an additional cam system can be provided to effect even moreaccurate positioning of the carriage member 14 relative to a workstation after the carriage member 14 has been disengaged from the drivechain 16 in the manner just described. As is shown in FIG. 5, a secondair cylinder 70 or the like is provided which is mounted on the carriagebed 12 and which actuates a notched cam surface 72. This notched camsurface 72 engages a cam surface engaging member 74, such as a simplepin or the like, which is also secured to the bottom surface of theportion 56 of the carriage member 14. After the carriage member 14 isstopped in the manner described above, the air cylinder 70 is energized,and the notched cam surface 72 is extended to engage the pin 74. If thecarriage member 14 has stopped in a position which is somewhat forwardor behind the desired stopping position, the notched surface 72 engagesthe pin 74 and drives the pin into the center of the notched surface 72,thereby positioning the carriage member 14 in the desired predeterminedposition relative to the work station (which is, of course, not shown inFIG. 5).

In the preferred embodiment of the invention, the air cylinders andmoving elements just described are secured to the carriage bed 12 andthe ramp surface 64 and the pin 74 are secured to the carriage member14. However, those skilled in the art will obviously appreciate thateither or both of these arrangements may be reversed, if so desired.

In the preferred embodiment of the invention, and as was suggested inthe plan drawings of FIGS. 1 and 2 above, buffer stations are providedimmediately in advance of each of the work stations. These bufferstations reduce the overall cycle time of the system. When the carriagemembers 14 are advanced to the next work station, only the time requiredfor carriage transfer from the buffer station to the adjacent workstation need expire before the work stations can begin their operation.The longer time period required for carriage transfer from a workstation to the buffer station of the next work station is effectedsimultaneously with the work station time. It is obvious that preciselocation of a carriage member 14 is not necessary when it is in one ofthe buffer station positions. Accordingly, at each buffer station it isonly necessary to provide the air cylinder 68 to drive the stop member66 into the path of the ramp surface 64.

As was noted in the beginning of this specification, one of the primaryfeatures of the present invention is that it is possible to achieveaccurate positioning of the workpiece in the work station despiteinexpensive, relatively non-accurate positioning of the work stationrelative to the conveyor system. FIGS. 6, 7, and 8 illustrate the meanswhereby this is achieved.

FIG. 6 is an elevational view of the conveyor bed 12, a carriage member14 and a typical work station the relationship of these componentsbefore the platen 58 has been lifted from the carriage member, and FIG.7 is a top plan view of the arrangement of FIG. 6. The followingdescription is a simultaneous description of FIGS. 6 and 7, with thesame reference numerals being used to indicate the same elements andcomponents in the drawings.

The carriage member 14 is supported on the conveyor bed 12 in the mannerdescribed above. Carriage member 14 supports separable platen 58, whichholds workpiece holding tooling 70, which itself holds workpiece 72.Platen 58 is positioned, but no fastened, to carriage member 14 by meanssuch as the tapered alignment pins 60 (also shown in FIG. 3) whichengage mating holes 74 in platen 58.

The work station 18 includes a column 76 supported on a base 78 which ismounted in a fixed, but not necessarily accurately positionedrelationship to the conveyor bed 12, such as by being bolted to a floor80 to which the conveyor bed 12 is also bolted through the legs 82 andfoot 84.

Section 18 also includes an elevator platform 86 which is positioned sothat, when it is in the lower position, such as is shown in FIG. 6, itis located beneath the carriage member 14 and the platen 58.

In accordance with the present invention, the work station 18 itselfincludes alignment means such as a pair of tapered alignment pins 88positioned on the upper surface of elevator platform 86. Matingalignment holes 90 are positioned in platen 58. Whenever elevatorplatform 86 is raised, such as by one of the linear motion modulesdescribed in FIGS. 10 through 14 below, the alignment pins 88 engagetheir mating holes 90 in platen 58 and the post 92 engages the bottomsurface of platen 58 to provide secure, accurate positioning of platen58 with respect to other tooling at work station 18 so that accuratework and assembling can be done despite the relatively non-accuratepositioning of work station 18 with respect to conveyor bed 12. When thework is completed, elevator platform 86 is lowered back to the positionshown in FIG. 6, and platen 58 is returned to carriage member 14, whereit is again positioned by the tapered alignment pins 60 on carriagemember 14 and the mating alignment holes 74 on platen 58.

FIG. 8 is an elevation view similar to FIG. 6, but shows the elevator 86in its raised position, supporting the platen 58 in an accurate positionrelative to the other positions and tooling at work station 18.

To illustrate the effectiveness of this portion of the invention,typical machines have been built in which the taper pin diameters wereapproximately one inch, the work stations were positioned up to onequarter inch from their nominal positions and the carriage memberstopping position was up to one quarter inch off of its nominalposition. Still, platen transfer was effected and positioning accuracywithin the work station was achieved within 0.001 inch.

While in the preferred embodiment, alignment means such as the taperedpins are positioned on the carriage member 14 and the elevator platform86, while corresponding mating holes are provided in the platen 58, itis obvious that alignment pins could be provided on the platen andcorresponding mating holes provided on the carriage member of theelevator platform. Also, alignment means other than tapered pins andmating holes could be used, so long as they are capable of providing thenecessary translation to the platen to overcome any inaccuracies in therelative positioning of the conveyor bed and work station or any errorsin the stopping position of the carriage member.

As was noted above, the principal purpose of an automatic assemblymachine such as is being described in the specification is themanipulation of parts and tools. The previous portion of thisspecification has described how the workpiece is conveyed to the workstation and then accurately positioned at the work station. Theremainder of the specification describes the manner in which the workstation performs its assembly operation on the workpiece after theworkpiece is accurately positioned at the work station.

Most manipulating motions can be resolved into linear motion componentsand rotary motion components performed in a desired sequence. Thepresent invention provides means to produce such motions by a chain ofstandardized motion modules coupled together, each module in the chainproviding one component of the total desired motion. The motion modulesare of standard design but have provision for adjustable stroke, speed,deceleration and multiple stop positions. The coupling of the motionmodules into a chain is provided by standardized plug and socket joints,so that no special parts need be engineered or built for eachapplication. Similar standardized plug and socket joints are utilized tomount the first motion module in the chain to the support column at thework station and for the attachment of a tool to the last module of thechain. It is the motion of the tool actually connected to the lastmodule in the chain which performs the assembly operation or the like onthe accurately positioned workpiece.

FIG. 9 is a schematic representation of a typical work station 18 inaccordance with the present invention. As is shown in FIG. 9, the workstation 18 includes a support column 76 which supports the elevatorplatform 86, which in turn supports the platen 58, the workpiece holdingtooling 70 and the workpiece 72, in the manner described in FIGS. 6, 7and 8 above. The elvator platform 86 is supported from column 76 by alinear motion module 100, such as is described in FIGS. 10 through 14,described below.

The column 76 also supports a chain of motion modules including ahorizontal linear motion module 102 and a vertical linear motion module104 such as are described in FIGS. 10 through 14 below. Vertical linearmotion module 104 supports a rotary motion module 106, such as isdescribed in detail in FIGS. 15 and 16 below. Rotary motion module 106in turn supports the tool 108 which is to perform the actualmanipulative procedure on the workpiece 72.

The column 76 also supports a control box 110 which controls the timingand sequence in which the motion modules 100, 102, 104 and 106 areactuated. By selectively energizing these motion modules, the workpiece72 is properly positioned and the tool 108 can be moved left or right,up or down and rotated clockwise or counterclockwise.

FIG. 10 is a plan view of a typical linear motion module 112 for use inthe work station 18 of FIG. 9 above. FIG. 11 is a cross-sectional viewtaken along the lines 11--11 of FIG. 10. The following description is ofFIGS. 10 and 11 simultaneously, with the same reference numerals beingused to indicate like parts and components in the two drawings.

As is shown in FIGS. 10 and 11, the linear motion module 112 includes astationary structure including a spar member 114, a shaft 116 and a pairof brackets 118 and 120 which support the spar 114 and the shaft 116 inspaced, parallel relationship. The linear motion module 112 alsoincludes a moving member 122 which, as is described below, is attachedto the spar member 114 and the shaft 116 for sliding reciprocal movementalong a defined path parallel to the spar member 114 and shaft member116 between limit stops supported by the stationary structure atpredetermined positions along this defined path.

The components from which the linear motion module 112 is constructedare themselves designed to have maximum stiffness with minimum weight inorder that the motion modules can be assembled in a cantilever manner toform a chain, as was shown in FIG. 9 above, with minimum bending ordeflection of the chain. Thus, since the motion module 112 of FIG. 10 isintended to be supported in the general area of its end 124, the tubularmember from which the spar 114 is constructed can be, if desired,constructed so that its walls are of a tapering thickness, as shown inFIG. 10, with the thicker portion of the wall being towards the end 124.Also, if the particular module is the first module in the chain and isintended for motion in a direction parallel to the support column of thework station, the support column itself can serve as the spar member114.

Continuing the description of FIGS. 10 and 11, moving member 122 isguided on shaft 116, preferably by means such as ball bearings 126, andis prevented from rotating about shaft 116 by a pair of rollers 128 and130. Rollers 128 and 130 are supported by moving member 122 and roll onthe outer surface of spar member 114. The axle of roller 128 is rigidlyfixed to the moving member 122 and the axle of roller 130 is springloaded on moving member 122 towards spar member 114. If the ballbearings 126 have an interference fit on the shaft 116, this combinationof bearings and rollers provides both zero looseness and zero binding atevery point along the path through which moving member 122 moves. Fixedroller 128 and spring loaded roller 120 are positioned so that the fixedroller 128 is placed on the side which resists the external torque whichis applied to moving member 122.

In the preferred embodiment of the invention, the components thus fardescribed in linear motion module 112 are constructed from the followingmaterials: Shaft 116 is preferably a precision ground and hardened roundsteel shaft and ball bearings 126 are preferably ball bushings, both ofwhich are readily available as commercial components. However, ifdesired, non-round shafts, rolling ball bearings, or even non-rollingbearings could be used for these components. The spar member 114 ispreferably of cold drawn steel tubing and need not be ground for mostapplications. Variations in diameter are absorbed by the spring loadedroller 130 and imperfect straightness does not effect the accuracy ofrepeatability of the stopping points. Moving member 122 is preferably ofminimum weight and maximum stiffness, and is typically fabricated as ahollow box using commercial rectangular steel tubing modified by weldingand machining.

Continuing the description of FIGS. 10 and 11, the end of the movingmember 122 which is remote from the spar member 114 has a socket 132therein in which another similar module or a tool holder may be mounted.Socket 132 is preferably made as a split hole closed by screws 134.Socket 132 is capable of supporting the spar member of another suchlinear motion module or a rotary motion module such as is described inFIGS. 15 and 16 below.

Moving member 122 is urged forward and backward along its defined pathby suitable drive means such as fluid power piston and cylinder 136,typically an air cylinder, although hydraulic cylinders can be used.Cylinder 136 is preferably secured to the bracket 120 and drives themoving member 122 by the shaft 138. Flow control valves 140 and 142control the speed and direction of energization of the cylinder 136.

Obviously, an electric motor driving a suitable arrangement such as alead screw or a rack and pinion could also be used to move the movingmember 122 along its defined path.

The travel ov moving member 122 is accurately limited in each directionby a stop assembly which includes a stop rod 144, a pair of limit stopssuch as adjustable stop nuts 146 and 148 and a control means 150, shownsupported by bracket 118. When moving member 122 contacts either thestop nut 146 or 148, thereby moving stop rod 144 within control means150, this provides a control signal indicating that the moving member122 has reached the end of its defined path. Details of several suchcontrol means are shown in FIGS. 12 and 13, described below.

FIG. 12 shows a cross-sectional view of a portion of the linear motionmodule of FIGS. 10 and 11, and particularly illustrates details of apreferred embodiment of the control means 150 which responds to themoving member 122 reaching the limits of its defined path. As is shownin FIG. 12, the stop rod 144 extends through the bracket 120, the movingmember 122 and the bracket 118. Mounted on stop rod 144 is a piston 152moving in a cylinder comprising cylinder heads 154 and 156 and acylinder body 158. At one end position of piston 152's possible travel,surface 160 on the piston strikes cylinder head 154 and at the other endposition, surface 162 on the piston 152 strikes cylinder head 156. Thereis a small clearance 164 between the piston and the cylinder body, andwhen the cylinder is filled with a fluid such as oil, that fluid passesslowly through this clearance, and causes a drag on the piston andtherefore a slow creeping of the stop rod 144 as it approaches one ofthe above-mentioned end positions.

The control means 150 also includes a bracket 166 which supports a pairof limit switches 168 and 170, mounted on either side of an arm 172which is secured to the stop rod 144.

In operation, whenever the moving member 112 is moving along any portionof its defined path other than the ends of its defined path, movingmember 122 passes freely around stop rod 144. However, whenever movingmember 122 approaches the end of its defined path, it strikes one of thestop nuts 146 and 148, and this imparts a movement to the stop rod 144.When this occurs, the above-described piston and cylinder arrangementprovides a dashpot effect as the stop rod 144 moves the piston, and theassembly causes a hard stop of the stop rod 144, and thus of the movingmember 122, when one face of the piston 152 strikes its respective endof the cylinder. At this time, the arm 172 actuates the appropriate oneof the limit switches 168 and 170 to provide a signal indicating thatthe moving member 122 has completed its motion and is now at the end ofits defined path.

In the preferred embodiment of the invention, in which air cylinders areused to drive the moving member 122, the cylinder remains energized,even though the moving member 122 is now being held firmly in itsstationary end position, and the signal provided by the limit switches168 and 170 are provided to the control box 110 (See FIG. 9) to indicateto the work station 18 that the portion of the stroke of the linearmotion module 112 has been completed. Obviously, if desired, this signalcould also be used to deenergize the drive means for the moving member122.

In a slight modification of the embodiment just described if desired, adashpot assembly could be used which does not have what is, in effect, acontrolled leakage between the walls of the piston and the cylinder tointerconnect the two ends of the cylinder. Instead, an externalconnection between the two ends of the cylinder could be provided, witha needle valve or the like in this external connection to control theamount of cushioning provided by the dashpot.

FIG. 13 shows a cross-sectional view similar to FIG. 12, and illustratesanother embodiment of the control means 150 which may be used with theinvention. As is shown in FIG. 13, a tube 174 is secured to the bracket118. Tube 174 supports retaining rings 176 and 178, washers 180 and 182,stop sleeve 184 and centering spring 186. A stop member 188 is providedwhich is secured to the end of stop rod 144 and is supported radially bythe washers 180 and 182. Axial movement of the stop member 188 islimited by shoulder 190 striking washer 182 and by retaining ring 192striking washer 180.

In operation, when moving member 122 moves to the left in FIG. 13, itmoves freely around stop rod 144 until it reaches the end of its definedpath, at which time it strikes stop nut 148 and pushes stop rod 144towards the left. When this occurs, stop member 188 pushes washer 190against the resistance of centering spring 186 until washer 190compresses stop sleeve 184 against washer 180 and retainer ring 176,which results in a hard stop of moving member 122.

Similarly, when moving member 122 moves to the right, it is stopped bypressure through the chain stop nut 146--stop rod 144--stop member188--retaining ring 192--washer 180--stop sleeve 184--washer 182 andretaining ring 178.

Limit switches 194 and 196 are supported in any suitable manner (notshown in FIG. 13) by the bracket 118 and are operated by the stop member188 at the corresponding limits of its travel. These limit switches maybe either electrical or pneumatic, depending upon the medium preferredfor the control and sequencing circuitry, and perform the same functionas the limit switches 168 and 170 of FIG. 12. Accordingly, theirfunction is not further described here.

Decelerating valves 198 and 200 are similarly supported by bracket 118and are operated by the stop member 188 a short distance before the endof travel of the stop member 188. These valves switch speed controlorifices in the power cylinder circuit, thereby permitting the cylinderto move faster in mid-stroke and slower at the ends of the stroke tominimize impact. In the case of electric motor drives, decelerationvalves 198 and 200 may be replaced by electrical switches which have thesame effect.

It is sometimes desirable that a linear motion module such as has beendescribed have intermediate stops other than the two ends stops whichhave been described. This can be achieved by mounting two or more linearmotion modules in the chain with their shafts and spars parallel.However, intermediate stops may also be provided on a single linearmotion module. In FIG. 15, an intermediate stop interposer 202 is guidedin block 204 and is extended and returned by a solenoid or cylinder 206and spring 208. This interposer assembly is mounted on spacers 210 onmoving member 122. The length of these spacers determines the locationof the intermediate stop. When interposer 202 is extended, such as byenergization of the solenoid or cylinder 206, it strikes the stop nut146 and moves the stop rod 144 just as the body of the moving member 122does, but at a different position of moving member 122. When thisoccurs, motion of the moving member 122 is stopped in the same mannerdescribed above. Now, when it is desired for moving member 122 to leavethe intermediate stop and continue to its end stop, the interposer 202is retracted and operation continues as described above.

FIG. 14 shows yet another alternate embodiment to limit travel of movingmember 122 and to provide control signals indicating that the movingmember 122 has completed its journey along the predetermined path. Apair of threaded rods 210 and 212 are provided which are supported bythe brackets 118 and 120. Insulators 214 and 216 are positioned alongthe threaded rods 210 and 212, as by nuts 218. By adjusting nuts 218,the position of the insulators 214 and 216 are moved, thereby definingthe limits of the defined path through which the moving member 122moves.

Insulator 214 carries a combination stop pin and electrical contact 220and insulator 216 carries a combination stop pin and electrical contact222. Combination stop pins and electrical contacts 224 and 226 aresupported by insulator 228 on moving member 122. When the moving member122 moves to the left and reaches the end of its defined path, themoving contact 224 strikes the stationary contact 220, thereby bothlimiting motion and closing a circuit (not shown) in FIG. 14, indicatingthat moving member 122 has reached the end of its defined path.Similarly, when moving member 122 reaches the end of its defined path tothe right, moving contact 226 strikes stationary contact 222, againstopping motion and completing an electrical circuit.

It has been found in practice that, because the electrical contactpressure in this embodiment is the full drive cylinder force, typicallymany pounds, stainless steel stop pins perform quite well bothmechanically and electrically, even though a control circuit voltage ofonly 24 volts is chosen for safety in exposed contacts andpermissibility of non-armoured wiring.

FIGS. 15 and 16 illustrate a typical rotary motion module in accordancewith the present invention. FIG. 15 is a side view of such a rotarymotion module and FIG. 16 is an end view of the rotary motion module andalso shows the series connection of two rotary motion modules. Thefollowing is a description of these two figures simultaneously, with thesame reference numerals being used to indicate like parts and componentsin the two drawings.

The rotary motion module 250 includes a stationary structure and amovable, rotating portion. The stationary structure includes a rotarycylinder 252 which is supported from a spar 254 by a bracket 256. Suchrotary cylinders, in which a vane is rotated by application of airpressure or the like, thereby causing rotation of a shaft 258, andcommercially available components. A typical such rotary cylinder issold under the trade name "ROTAC", made by the X-Cel-O Company. Thedimensions of the spar 254 are chosen so that it fits into the socket ofthe moving member of the linear motion module described in the abovefigures, whereby the rotary motion module 250 may be positioned in achain of such motion modules as shown in FIG. 16.

A mounting disc 260 is provided which is secured to the front of therotary cylinder 252 and through which the rotating shaft 258 passes. Acircular groove 262 is provided in the surface of mounting disc 260 andtwo stop blocks 264 and 266 are keyed and clamped in the groove 262 indisc 260. The stop block 264 carries an adjustable stop screw 268 and alimit switch 270. similarly, stop block 266 carries an adjustable stopscrew 272 and a limit switch 274.

A moving member or arm 276 is carried by the cylinder shaft 258 androtates with shaft 258 whenever the cylinder 252 is energized. In amanner similar to that described in the stop and limit mechanisms of thelinear motion modules described above, the arm 276 rotates until itcontacts one of the stop blocks 264 or 266, at which time a hard stopmotion limit is provided and a control circuit is energized, through theappropriate limit switch, to indicate that the rotary motion has reachedthe end of its defined path.

The rotatable shaft 258 also carries a tool mounting flange 278 on whichcan be attached either a tool to perform a desired function on aworkpiece or a spar mounting adaptor into which another motion module,either a linear motion module or a rotary motion module, can be pluggedto complete or continue a chain of such motion modules, as was shown inFIG. 9 above and in FIG. 16.

It is obvious that, although no dashpot mechanism is shown in FIGS. 15and 16, if it is desired to cushion the stop of arm 276 when it reachesthe stop blocks 264 or 266, a dashpot assembly similar to the onesdescribed above in connection with the linear motion modules could beadded to the rotary motion module.

While the invention is thus disclosed, and several preferred embodimentsdescribed in detail, the invention is not limited to these shownembodiments and structures. Instead, many modifications will occur tothose skilled in the art which lie within the spirit and scope of theinvention. It is thus intended that the invention be limited in scopeonly by the appended claims.

What is claimed is:
 1. A rotary motion module for imparting controlled,rotary motion to an element comprising, in combination:a rotary cylinderincluding a housing and a rotor, controllable drive means which, whenenergized, drives the rotor of the rotary cylinder, clampable modulesupport means secured to the housing of the rotary cylinder, an armsecured to the rotor of the rotary cylinder, limit means secured to thehousing of the rotary cylinder at a predetermined position around therotor in the path traversed by the arm when the drive means isenergized, control means responsive to the arm contacting the limitmeans to provide a control signal indicating that the arm has contactedthe limit means, and module output clamp means secured to the rotor tosupport the element to be moved and adapted to receive the clampablemodule support means of the rotary motion module, whereby a plurality ofrotary motion modules may be connected in a chain to form a compoundmotion machine.
 2. The rotary motion module of claim 1 which furthercomprises a plate secured to the housing of the rotary cylinder whichhas an aperture therein through which the rotor extends, the platehaving an annular groove therein which is concentric with the rotor, andin which the limit means are adjustable stop blocks which are clamped tothe groove.